The levers can be regulated, and with the right tool I think it’s easy enough for you to do it yourself. I believe you can either adjust the tuning pin on the neck with a certain tool (you could ask lyon & healy or a harp tech), or you can adjust the height of the lever slightly with the right screwdriver. The buzzes might disappear with those sorts of adjustments too, though is it possible the neck is twisting a little causing those strings to come into contact with their levers? Are they buzzing if you have the lever engaged as well?